as in treacherous
formal
causing harm in a way that is gradual or not easily noticed
Most people with this insidious disease have no idea that they are infected. an insidious enemy
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Recent Examples of insidious
It's aptly named after LV-426, the infamous planetoid that the interstellar towing vessel USCSS Nostromo set down upon to discover the derelict spaceship and its insidious contents in the classic 1979 feature film.
—
Jeff Spry, Space.com, 27 Apr. 2026
Hillsides covered in fuel The hills surrounding Concepción, Penco and Lirquén appear deep green from the air, carpeted in trees, and in the thickness of these forests lies an insidious risk.
—Stefano Pozzebon, CNN Money, 26 Apr. 2026
Public narratives that frame low teen birth rates as a problem will only intensify these insidious efforts by introducing new people to pronatalist beliefs and fostering support for efforts that undermine contraceptive access.
—Riley J. Steiner, STAT, 20 Apr. 2026
After all, offenses committed by individuals in positions of public trust are especially insidious.
—Craig MacLellan, Boston Herald, 3 Apr. 2026
See All Example Sentences for insidious
Jeff Spry, Space.com, 27 Apr. 2026
Hillsides covered in fuel The hills surrounding Concepción, Penco and Lirquén appear deep green from the air, carpeted in trees, and in the thickness of these forests lies an insidious risk.
—Stefano Pozzebon, CNN Money, 26 Apr. 2026
Public narratives that frame low teen birth rates as a problem will only intensify these insidious efforts by introducing new people to pronatalist beliefs and fostering support for efforts that undermine contraceptive access.
—Riley J. Steiner, STAT, 20 Apr. 2026
After all, offenses committed by individuals in positions of public trust are especially insidious.
—Craig MacLellan, Boston Herald, 3 Apr. 2026
See All Example Sentences for insidious
Recent Examples of Synonyms for insidious
Adjective
-
So for graduates walking into a treacherous student debt landscape, even a single round of loan forgiveness can help.—
Sydney Lake,
Fortune,
13 May 2026
-
Under the cover of darkness, the Traitors murder the Faithful one by one in a treacherous spree while the Faithful try to uncover the Traitors and banish them from the game.—
Nellie Andreeva,
Deadline,
11 May 2026
Adjective
-
Is there a subtle way to say something?—
Judith Martin,
Sun Sentinel,
14 May 2026
-
Many viewers interpreted the scene as a subtle reference to Sweeney's political beliefs after BuzzFeed reported in August that Sweeney was registered as a Republican in Florida.—
Anthony Robledo,
USA Today,
13 May 2026
Adjective
-
On May 14, Dana Williamson, a former top aide to Newsom and onetime Becerra political adviser, pleaded guilty in federal court after accepting a plea deal to multiple charges, including committing bank and wire fraud, filing a false tax return, and lying to the FBI.—
James Ward,
USA Today,
15 May 2026
-
Dana Williamson, former top aide to Newsom, pleaded guilty in an FBI corruption probe to bank fraud, filing a false tax return and lying to the FBI.—
Sacbee.com,
Sacbee.com,
15 May 2026
Adjective
-
The plaintiffs in the California suit claim they were misled by deceptive labeling when purchasing the product more than a dozen times in California stores.—
Itzel Luna,
Chicago Tribune,
13 May 2026
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Patel’s complaint against FanDuel includes claims for negligence, intentional infliction of emotional distress, conspiracy, and deceptive and unfair trade practices.—
Michael McCann,
Sportico.com,
12 May 2026
Adjective
-
Pakistan was a perfidious ‘ally’ in Afghanistan, backing the Taliban while pretending to be our friends.—
Efrat Lachter,
FOXNews.com,
18 Apr. 2026
-
The government took a genuine invitation to collaborate as a perfidious power grab.—
Gideon Lewis-Kraus,
New Yorker,
14 Mar. 2026
Adjective
-
Vanegas, who has lived at Forest View Mobile Home park for two years, stood at the culmination of a nearly yearlong effort to save the park after Blue Island officials ordered the property owners to evict residents, citing unsafe conditions, incorrect zoning, unpaid water debt and code violations.—
Addison Wright,
Chicago Tribune,
13 May 2026
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Similarly unimpressive, if not technically incorrect, is Sieger’s dish.—
Roxana Hadadi,
Vulture,
12 May 2026
Adjective
-
The challenge these proposals aim to address is real — but trying to hold back the tide is the wrong answer.—
Editorial,
Boston Herald,
10 May 2026
-
In a 4-3 ruling, the court said the legislature followed the wrong process for putting the question, an amendment to the state constitution, on the ballot.—
Larry Kaplow,
NPR,
9 May 2026
Cite this Entry
“Insidious.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/insidious. Accessed 16 May. 2026.
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